ES2359427T3 - METHOD FOR PREPARING MICRO-FLUID DEVICES AND RESULTING DEVICES. - Google Patents

Abstract

A method of making a microfluidic device by providing first and second substrates and forming a first frit structure on the first substrate and a second frit structure on the second substrate and consolidating the first and second substrates together, with frit structures facing, so as to form a consolidated-frit-defined and consolidated-frit-surrounded recess between said first and second substrates, where the second substrate has at least one pre-formed through-hole therein, and where forming a second frit structure includes forming a frit layer within said through-hole covering the interior surface of the through-hole to a thickness sufficiently thin to produce, on consolidating the substrates and the first and second frit structures together, a through-hole having an interior surface of consolidated frit continuous with the consolidated frit surrounding the recess.

Description

Background

In general, the present invention relates to microfluidic devices useful in chemical processes, and in particular to microfluidic devices formed by a consolidated and structured frit that defines recesses or conduits in a volume between two or more substrates.

As interpreted herein, microfluidic devices are generally devices that contain fluidic conduits or chambers that typically have at least one and generally more dimensions in the range of sub-millimeters to one millimeter. Microfluidic devices can be useful for chemical reactions and difficult, dangerous or otherwise impossible processes can be carried out in a safe, efficient and environmentally friendly way.

Microfluidic devices formed by a consolidated and structured frit that define recesses or ducts in a volume between two or more substrates have been developed in previous work by partners of the present inventor (s), as disclosed in U.S. Patent No. 6,769,444, "Microfluidic Device and Manufactured Thereof" and in related patents or patent publications. The methods disclosed therein comprise several stages including providing a first substrate, providing a second substrate, forming a first frying structure on one of the support surfaces of said first substrate, forming a second frying structure on one of the support surfaces of said substrate. second substrate, and consolidate said first substrate, said second substrate and said first and second frit structures all together, with support surfaces facing each other, to form a recess defined by a consolidated frit between said first and second substrates. While the manufacturing methods disclosed in this way have proved useful for producing devices of the type described herein, it is desirable to increase the efficiency, in particular the performance, of the processes by which said devices are produced.

Summary of the invention

One aspect of the invention is a method for preparing a microfluidic device by providing a first and second substrates and forming a first frit structure on the first substrate and a second structure on the second substrate and consolidate the first and second substrates together, with the fritaorientadas structures, so that they form a recess defined by consolidated frit and surrounded by frit consolidated between the first and second substrates, in which the second substrate has at least one pre-formed perforated hole, and in which the formation of the The second frit structure includes forming a frit layer inside said pass-through hole that covers the inner surface of the through hole with a thickness thin enough to produce, once the consolidation of the substrates and the first and second frit structures is produced. together, a through hole that has an inner frit surface with solid that is in contact with the consolidated frit that surrounds the recess.

Another aspect of the invention relates to a microfluidic device that includes a consolidated frit, a first substrate and a second substrate; the consolidated frit, the first substrate and the second substrate are joined together by means of the consolidated frit, the consolidated frit surrounds at least a first recess between the first and second substrates, the first recess is in fluid communication with a through hole that it extends through said second substrate, and in which the through hole is internally coated with the consolidated frit that is in contact with the consolidated frit surrounding the recess, providing a single material interface inside the device.

The following detailed description explains additional features and advantages of the invention, and in part these will be apparent to those skilled in the art from that description or may be recognized by the practice of the invention as described herein, including the detailed description. Next, the claims, as well as the attached drawings.

It should be understood that both the preceding general description and the following detailed description present embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as claimed. The accompanying drawings are included to provide a better understanding of the invention, and are incorporated and constitute part of this specification. The drawings illustrate various embodiments of the invention and, together with the description, serve to explain the principles and operations of the invention.

Brief description of the drawings

Figures 1A-1E are cross-sectional views of substrates processed in accordance with an embodiment of the method of the present invention to form an embodiment of a device of the present invention.

Figure 2 is a cross-sectional view of another embodiment of a device of the present invention that can be produced by means of an embodiment of the method of the present invention.

Figures 3A-3C are cross-sectional views of substrates processed in accordance with an aspect of an embodiment of the method of the present invention.

Figures 4A-4B are cross-sectional views of substrates processed in accordance with another aspect of an embodiment of the method of the present invention.

Figure 5 is a cross-sectional view of a part of another embodiment of a device of the present invention that can be produced by means of the aspect of the method depicted in Figures 3A-3C and / or 4A-4B.

Figures 6A-6E are cross-sectional views of substrates processed in accordance with two other aspects of an embodiment of the method of the present invention.

Figures 7A-7C are cross-sectional views of substrates processed in accordance with another aspect of an embodiment of the method of the present invention.

Figure 8 is a cross-sectional view showing the consolidation profiles before and after a sufficiently thin fried layer in a through hole of an outer substrate.

Figure 9 is a cross-sectional view showing the consolidation profiles before and after a slightly thicker fried layer in a through hole of an outer substrate.

Figure 10 is a cross-sectional view illustrating the consolidation profiles before and after a considerably thicker fried layer in a through hole of an outer substrate.

Figure 11 is a cross-sectional view showing the consolidation profiles before and after a sufficiently thin frying layer in a through hole of an inner substrate.

Figure 12 is a cross-sectional view showing the consolidation profiles before and after a slightly thicker frit layer in a through hole of an inner substrate.

Figure 13 is a cross-sectional view illustrating the consolidation profiles before and after a considerably thicker fried layer in a through hole of an inner substrate.

Figure 14 is a grayscale digital photograph of a through hole of a substrate of a microfluidic device produced in accordance with an embodiment of a method of the present invention before final or total consolidation.

Figure 15 is a grayscale digital photograph of the through hole of a microfluidic device of Figure 14 after final or total consolidation.

 Detailed description of the preferred embodiments

Reference will now be made in detail to the preferred embodiments of the invention, the examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numbers are used in all drawings to refer to the same part or parts.

Figures 1A-1E are cross-sectional views of the substrates 102 and 104 processed in accordance with an embodiment of a method of the present invention to form an embodiment of a device of the present invention.

The present invention involves the formation and processing of the bound frit, which means a frit that is adhered in some way before and after the forming process, such as by an organic binder or other or by any other appropriate means. The present invention also involves the frying or consolidation of the frit, which means the final densification and solidification of the frit material, such as by sintering or by any other appropriate means. The partial consolidation of the frits means to process the frit to take it only partially towards the final consolidated state.

Figure 1A shows a first and second bare substrates 102 and 104. Desirably, the first and second substrates 102 and 104 are flat. They may be of various appropriate materials, such as glass, ceramic and ceramic materials. In general, low values of CTE and high values of thermal conductivity are desired, as reasonably due to good compatibility with the frit material and with the frit consolidation processes. Transparency for inspection, assessment and control flexibility is also desirable. In the particular cross-section of the figure, there is a through hole 108 that extends through the substrate 104.

Figure 1B shows a first and second substrates 102 and 104 after the formation of structures 202 and 204 of frit bonded on them has occurred, such as by a molding process. The linked frit structures have been shaped on the upper surfaces 302 and 304 of the substrates 102 and 104 with the orientation shown in the figure, but the orientation may vary during forming or related processing as desired. Surfaces 302 and 304 may be referred to as support surfaces of substrates 102 and 104, since surfaces 302 and 304 are oriented facing each other in the final conformation of the resulting device. The first frit structure 204 of the embodiment of Figure 1 includes a layer 308 of frit placed on the inner surface of the through hole 108.

Figure 1C shows frit structures 202 and 204 on substrates 102 and 104 after partially detaching or detaching or partial consolidation of the frit.

Figure 1D shows the structures of frit 202 and 204 partially dislodged or partially dislodged or consolidated in contact with one another to carry out the final consolidation, such as by means of deinterlination. Partially detached or unbound or other partial consolidation, under appropriate conditions, can improve the strength and cohesiveness of frit structures. Alternatively, however, the frying structures formed in this way (not partially unbound or consolidated) can be stacked together and detached and / or consolidated in one process or in successive processes.

Figure 1E shows substrates 102 and 104 and frit structures 202 and 204 after final consolidation as by sintering. The frit structures 202 and 204 are subjected to consolidation with the substrates 102 and 104 and between them to give rise to one or more recesses 110 defined by existing consolidated frit between the first and second substrates 102 and 104. The resulting microfluidic device 10 includes a consolidated frit 202, 204 and a first substrate 102 and a second substrate 104, all of them joined together by means of the consolidated frit 202, 204. At least one recess 110 existing between the first and second substrates 102 and 104, defined by the consolidated frit 202, 204, it is in fluid communication with the through hole 108 that extends through the second substrate 104, and the part of the consolidated frit 202, 204 resulting from the layer 308 is positioned such that the interior surfaces of the first relevant recess 110 and the through hole 108 are formed by consolidated frit, and in such a way that the consolidated frit lining inter The through hole 108 is in contact with the consolidated frit that internally covers the recess 110.

Figure 2 is a cross-sectional view of another embodiment of a device of the present invention that can be produced by means of an embodiment of the method of the present invention. In particular, Figure 2 illustrates that more than two substrates can be used. In the microfluidic device 10 of the figure, three substrates 102, 104 and 106 are present, and the resulting consolidated frit defines a recess 110 existing between the first and second substrates 102, 104 and a second recess 111 existing between the second and third substrates 104, 106 The first recess 110 and the second recess 111 are in fluid communication through the through hole 108, and the part of the consolidated frit resulting from a layer corresponding to the layer 308 is positioned such that the interior surfaces of the first recess 110, the second recess 111 and the through hole 108 are all formed by continuous consolidated frit. The structures resulting from the methods of the present invention can be extended to several substrates in parallel.

In accordance with the methods of the present invention, providing substrates including perforated orifices greatly improves manufacturing performance and the cost associated with the production of microfluidic devices of the type of those of the invention. Providing substrates with holes already present, one of the most important risks of breakage, that produced by retention drilling, is moved just before or at the same time of the first stage of the process. Therefore, the investment in frits forming processes on a given substrate is not subject to the risk of loss due to substrate breakage during hole drilling. In addition, a potential source of contamination, non-uniformities and inclusions, with respect to the previous process is eliminated, in which no chips or drill fragment are produced in the presence of structures of green fritted or unbound but not consolidated.

Furthermore, the process or method of the invention also allows the production of perforated holes coated internally with consolidated frit, both outside and in Figure 1E and inside the device as in Figure 2. This allows the production of a device. microfluidic comprising two or more substrates or pavements of materials that are chosen from glass, ceramic or ceramic-glass, or even other materials, the substrates or pavement remaining separately and joining together by means of a glass or glass-bound frit. ceramic existing between the substrates or successive pavements, and forming the fried walls that define ducts inside said device as well as forming a coating such that the interior surfaces of the device are completely covered with the consolidated frit. Thus, in a way, the materials and properties of the substrate and the frit can be chosen independently, to produce devices with higher performance than devices with similar materials. For example, one or more substrates can be chosen to obtain the highest thermal conductivity, while it is possible to optimize it fried in terms of chemical durability, in general, or in particular reaction conditions.

The layer 308 that internally covers one or more perforated holes 108 can be produced in several ways. For example, as shown in Figures 3A and 3B, the through hole 108 may be filled with a slit frit to form a frit structure 204. An adhesive film or other reinforcing material 120 may be used to contain the frit on the reverse side. of the substrate 104 during the filling of the through hole 108. After forming, if the frit formed in this way has sufficient strength, the resulting filling hole can be drilled, giving rise to a substrate 104 with a frit structure 204 thereon, in the one that the structure defines includes a layer 308 that internally covers the through hole 108 of the substrate 104, as shown in Figure 3C. Alternatively, if the frit formed in this way is not strong enough, the frit can be partially detached or detached, or otherwise it can be partially consolidated, resulting in a frying structure 204 partially or completely detached or partially consolidated as shown in Figure 4A, which can then be drilled, resulting in the structure of Figure 4B. The re-opening of the fried filler holes, whether filled with a frit shaped in this way or with a deep-grooved or partially unblocked frit

or partially consolidated, it is relatively simple and can typically be carried out with a high speed steel drill, generally without liquid cooling, in contrast to direct drilling on glass or ceramic substrates.

Multiple perforated holes in a given substrate may be desirable, and it is not required that the structure set with which the perforated holes are initially filled be a simple or flat frit structure. For example, structures such as those shown in Figure 5 may be desirable.

Figures 6A-6E show other ways of producing the layer 308 that internally covers one or more perforated holes 108. Figure 6A shows a substrate 104 placed in contact with a declavija or layer positioning plate 404. The pin or layer positioning plate 404 houses a structure that contains a plug-shaped plug 408, and is positioned with respect to the substrate 104 such that the plug 408 is located in the center or near the center of the hole 108 in the substrate 104, as shown in the Figure 6A. Advantageously, the plug can also project approximately the minimum intended thickness of the frit structure that must reach above the bearing surface 304. Subsequently, the frit structure 204 is formed on the substrate 104 and inside the remaining open parts of the hole 108, such as a medium for molding a frit and a binder mixture on the substrate 104, as shown in Figure 6B. Subsequently, the removal of the peg or layer 404 positioning plate with its pin 408 that accompanies it gives rise to the structure shown in Figure 6C, which can then be detached or partially detached or partially consolidated giving rise to material 204 of structured frit of Figure 6D.

When it is desired that the frit structure be present on both sides of the substrate 104, an additional pin or layer positioning plate 405 can be re-inserted with an additional plug 409, so that the pin positioning plate is on the side of the previously formed frit structure 204. This step can be carried out with the previous frit structure 204, in an unlinked or partially unlinked or partially consolidated state as shown, or even in a shaped state in this way, depending on the mechanical strength that structure 204 exhibits in the shaped state in this way. . If the structure 204 has a more complex shape than the simple flat shape shown, the additional ocapa pin positioning plate 405 may be smaller in terms of lateral reach than that shown in Figure 6E, or even noplana, with in order to favor the adjustment or the conformation on the possible complex form of the structure 204.

The embodiment of the methods of the present invention relating to Figures 3A-3C or Figures 4A-4B employs a substrate 104 with a through hole 108 that is first filled and then drilled, resulting in a layer of frit structure or material on the walls of the original hole. This particular alternative can also be adapted to substrates that have a frit structure on both sides. This is briefly shown in Figures 7A-7C. If it is required due to resistance, it is possible to partially or partially unlink or partially consolidate the frit structure 204 formed firstly on the substrate 104, as shown in Figure 7A (representing the densest and darkest filling of 204 of Figure 1). unbound or partially unbound or partially consolidated material). Subsequently, a second structured frit 205 can be formed on the remaining open main surface of the substrate 104 as shown in Figure 7B. Subsequently, the resulting filled hole can be drilled while the structure 105 is maintained in a shaped state in this manner, as shown in Figure 7C.

Figures 8-10 illustrate the sensitivity of the process of the invention to the thickness of the layer 308 of the frit placed on the inner surface of the through hole 108, in which the structure of the frit is placed only on one side of the substrate 104. Yes layer 308 is thin enough, as in the case of Figure 8, changes in the overall shape of the layer resulting from the consolidation process (represented by the downward arrows in the figure) are minimal, and the fry coating is maintained consolidated on the inner surfaces of the through hole 108 of the substrate 104. If the layer 308 is too thick, the resulting consolidating profile, as shown in Figure 9, may result in the exposure of the inner surface 904 inside the through hole 108 of the substrate 104, or in other words, the defolding of the coating can occur from the bare main surface of the substrate 104. When the layer 309 e s too thick, the resulting consolidated profile, as shown in Figure 10, exposes the internal surface 904 of the interior of the through hole 108 of the substrate 104 above and below the layer 308. Thus, it is desirable to use an appropriate fine structured frying coating. for layer 308.

Figures 11-13 illustrate the sensitivity of the process of the invention to the thickness of the layer 308 of the frit placed on the inner surface of the through hole 108, in which the frit structure is placed on both sides of the substrate 104. As It can be seen from the profiles of Figures 11 and 12, the internal surface of the through hole 108 is not devoid of coating during the consolidation process by using a thick layer 308. However, thin layers are preferred for better control of process and global counter-dimensional.

Desirably, the present invention can be used with glass, ceramic and / or glass ceramic substrates. Metal substrates can also be useful. While the CTE mismatch between the consolidated frit and the substrate must not be very large in order to be able to retain resistance to thermal gradients and thermal bumper, the present invention finds particular utility in allowing an optimization of the substrate and the frit materials separately, since the present invention allows the presence of a consolidated continuous continuous surface on the inner surfaces of microfluidic devices. For example, for many applications it is desirable to choose the substrate material in order to improve the thermal conductivity above that of the frit, and to choose and / or formulate the frit in order to provide the desired levels of chemical resistance or inert character.

Some additional beneficial effects of the invention can be seen from Figures 14 and 15. Figure 14 is a grayscale digital photograph of a through hole of a microfluidic device substrate produced in accordance with an embodiment of a method of the present invention before final or global consolidation. Figure 15 is a grayscale digital photograph of the through hole of microfluidic device substrate of Figure 14 after final or overall consolidation. The surface defects and largesity can be seen in Figure 14 in the form of small fragments of glass 602 and in the form of surface protuberances 604 and generally of sharp corners 606. In Figure 15, it is observed that the glass fragment 602 is covered and matched by the consolidated frit, and the surface roughness and bordesagudos have also disappeared. Thus, the potential points of mechanical stress concentration (points that are also more susceptible to chemical attack) are eliminated or reduced.

In general, the invention provides a microfluidic device comprising two or more separate substrates or floorings and joined together by means of a glass or ceramic-glass frit between the successive opaviment substrates, the frit forming walls that define ducts or chambers in the interior of said device and forming a coating such that the interior surfaces of the device are completely covered with the consolidated frit. This allows both (1) the flexible manufacture of various device geometries and that the ducts or chambers (except the drilled holes) are determined by an additive fritting process, and not by a more environmentally friendly process and / or a more difficult subtractive process, such as (2) flexibility in the optimization of materials, since it is possible to optimize the properties of the frying material in terms of contact with fluids while optimizing the properties of the substrate as regards resistance, thermal conductivity or thermal insulation and the like. In addition, the use of the method to prepare said devices disclosed herein reduces the cost of production and increases the yield by starting the production process with substrates that have perforated holes, transferring any loss of production during drilling or otherwise during the formation of the holes forward in the production cycle.

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Claims (10)

1. A method for preparing a microfluidic device (10), comprising: providing a first substrate (102); providing a second substrate (104) having at least one through hole (108) therein; forming a first frit structure (202) on the support surface (302) of said first substrate (102); forming a second frit structure (204) on the support surface (304) of said second substrate (104);  Y consolidating said first substrate (102) and said second substrate (104) and said first and second fried structures (202, 204) together, with the supporting surfaces (302, 304) facing each other, so as to form a recess (110) surrounded by consolidated frit between said first and second substrates (102, 104), the method being characterized by: the formation of a second frit structure (204) includes forming a frit layer (308) inside the through hole (108) of said second substrate, covering said frit layer (308) inside said pass hole (108) the inner surface of said through hole (108) to a thickness thin enough to produce, once said first substrate (102) and said second substrate (104) and said first and second frit structures (202, 204) together , a through hole (108) having a consolidated inner frit surface (308) that is in contact with the consolidated frit (202, 204) surrounding said recess (110).

2.

The method according to claim 1, wherein the formation of the frit layer (308) inside the through hole (108) of said second substrate comprises filling said through hole (108) with a fried ligand and piercing through of the resulting filled hole.

3.

The method according to claim 1, wherein the formation of the frit layer (308) inside the through hole (108) of said second substrate comprises filling said through hole (108) with a bonded frit, from bind said frit and then drill through the resulting filled hole.

Four.

The method according to claim 1, wherein the formation of the frit layer (308) inside the through hole (108) of said second substrate comprises placing a duct maintenance structure (408; 409) in the inside the through hole (108), and fill the resulting volume of the unoccupied hole through the duct maintenance structure (408; 409) with a frit linked, and remove the duct maintenance structure (408; 409).

5.

The method according to any of claims 1-4, wherein providing a first substrate

(102) comprises providing a glass, ceramic or glass-ceramic substrate.

6.

The method according to any of claims 1-5, wherein said material from which the first substrate (102) or said second substrate (204) is formed is chosen from a material having a higher coefficient of thermal conductivity than that of said frit (202, 204).

7.

The method according to any of claims 1-6, wherein said consolidated frit (202, 204) is chosen so as to have a degree of resistance to chemical attack greater than that of the material from which said first is formed. substrate (102) or said second substrate (104).

8.

A microfluidic device (10) comprising; a consolidated frit (202 + 204); a first substrate (102); and a second substrate (104); the consolidated frit (202 + 204), the first substrate (102) and the second substrate (104) are joined together by means of the consolidated frit (202 + 204), surrounding the consolidated frit (202 + 204) at least a first recess (110) existing between the first and second substrates (102, 104), said first recess (110) being in fluid communication with a through hole (108) extending through said second substrate (104),

the microfluidic device (10) being characterized in that said through hole (108) is universally coated with consolidated frit (308) which is in contact with the consolidated frit (202 + 204) that surrounds around (110).

9.

The microfluidic device (10) of claim 8, wherein it further comprises a third substrate (106) attached by means of consolidated frit (202 + 204) to the first and second substrates (102, 104), surrounding the consolidated frit (202 + 204) at least one second recess (111) existing between the second and third substrates (104,106), the first recess (110) being in communication with the second recess (111) by means of a through hole (108), the through hole (108) internally coated with consolidated frit (308) that is in contact with the consolidated frit (202 + 204) surrounding said first and second recesses (110, 111).

10.

The microfluidic device (10) of any one of claims 8 and 9 wherein the material from which it is forming one or more of the substrates (102, 104, 106) has a thermal conductivity greater than the consolidated fried dela (202 + 204).